| 摘要 |
An aqueous black ink for a writing process in which ink is transferred in droplets onto a print carrier. The ink comprises 25-42 g./l. of the direct Diamine Blue 6B, extra high concentration; 14-22 g./l. of the direct dye Diamine Scarlet 4BS, extra concentration; 290-430 ml./l. of formamide; 32-48 ml./l. of 90% diethanolamine, 24-60 g./l. of citric acid, a water-soluble and organic soluble disinfectant, and balance essentially water. A process for producing such an ink comprises the steps of mixing both dyes together; introducing the mixture at room temperature in incremental portions into the formamide and stirring until the dyes are substantially completely dissolved. Undissolved salts are removed from the mixture. Diethanolamine and distilled water are introduced under agitation into the mixture. The pH is adjusted to about 6 to 8 with citric acid and disinfectant is added. The mixture is filtered under vacuum and then gases are withdrawn by treating the mixture under a vacuum.
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